Add mention of shared-memory/disk for multi-master clustering.
Add mention of shared-memory/disk for multi-master clustering.

cjcjameson/gpdb,lintzc/gpdb,jmcatamney/gpdb,jmcatamney/gpdb,Quikling/gpdb,tpostgres-projects/tPostgres,postmind-net/postgres-xl,Chibin/gpdb,Quikling/gpdb,xuegang/gpdb,lintzc/gpdb,rvs/gpdb,Quikling/gpdb,zaksoup/gpdb,greenplum-db/gpdb,postmind-net/postgres-xl,adam8157/gpdb,randomtask1155/gpdb,oberstet/postgres-xl,foyzur/gpdb,kmjungersen/PostgresXL,foyzur/gpdb,snaga/postgres-xl,rvs/gpdb,jmcatamney/gpdb,Postgres-XL/Postgres-XL,ashwinstar/gpdb,arcivanov/postgres-xl,edespino/gpdb,yazun/postgres-xl,atris/gpdb,foyzur/gpdb,edespino/gpdb,Quikling/gpdb,lintzc/gpdb,tpostgres-projects/tPostgres,Chibin/gpdb,xinzweb/gpdb,lpetrov-pivotal/gpdb,foyzur/gpdb,CraigHarris/gpdb,foyzur/gpdb,pavanvd/postgres-xl,0x0FFF/gpdb,xinzweb/gpdb,techdragon/Postgres-XL,cjcjameson/gpdb,janebeckman/gpdb,kaknikhil/gpdb,xuegang/gpdb,zaksoup/gpdb,ashwinstar/gpdb,ashwinstar/gpdb,arcivanov/postgres-xl,atris/gpdb,rubikloud/gpdb,jmcatamney/gpdb,foyzur/gpdb,zeroae/postgres-xl,kmjungersen/PostgresXL,yuanzhao/gpdb,yazun/postgres-xl,xinzweb/gpdb,ovr/postgres-xl,zaksoup/gpdb,lintzc/gpdb,ashwinstar/gpdb,zaksoup/gpdb,lisakowen/gpdb,ahachete/gpdb,lpetrov-pivotal/gpdb,tpostgres-projects/tPostgres,chrishajas/gpdb,lpetrov-pivotal/gpdb,zaksoup/gpdb,yuanzhao/gpdb,janebeckman/gpdb,Chibin/gpdb,chrishajas/gpdb,kaknikhil/gpdb,Postgres-XL/Postgres-XL,royc1/gpdb,tangp3/gpdb,edespino/gpdb,lintzc/gpdb,greenplum-db/gpdb,lisakowen/gpdb,jmcatamney/gpdb,randomtask1155/gpdb,Postgres-XL/Postgres-XL,rubikloud/gpdb,lintzc/gpdb,rubikloud/gpdb,yuanzhao/gpdb,kaknikhil/gpdb,arcivanov/postgres-xl,adam8157/gpdb,royc1/gpdb,oberstet/postgres-xl,snaga/postgres-xl,tpostgres-projects/tPostgres,royc1/gpdb,zeroae/postgres-xl,royc1/gpdb,rvs/gpdb,50wu/gpdb,janebeckman/gpdb,50wu/gpdb,xinzweb/gpdb,cjcjameson/gpdb,Chibin/gpdb,lisakowen/gpdb,atris/gpdb,rvs/gpdb,greenplum-db/gpdb,zaksoup/gpdb,xinzweb/gpdb,50wu/gpdb,yuanzhao/gpdb,yuanzhao/gpdb,0x0FFF/gpdb,janebeckman/gpdb,randomtask1155/gpdb,ovr/postgres-xl,xinzweb/gpdb,50wu/gpdb,ashwinstar/gpdb,oberstet/postgres-xl,zeroae/postgres-xl,lintzc/gpdb,yazun/postgres-xl,0x0FFF/gpdb,royc1/gpdb,xuegang/gpdb,CraigHarris/gpdb,janebeckman/gpdb,foyzur/gpdb,snaga/postgres-xl,rvs/gpdb,xuegang/gpdb,yuanzhao/gpdb,lisakowen/gpdb,Chibin/gpdb,CraigHarris/gpdb,pavanvd/postgres-xl,Chibin/gpdb,50wu/gpdb,zeroae/postgres-xl,kaknikhil/gpdb,tangp3/gpdb,tpostgres-projects/tPostgres,tangp3/gpdb,Postgres-XL/Postgres-XL,ashwinstar/gpdb,kaknikhil/gpdb,lpetrov-pivotal/gpdb,CraigHarris/gpdb,kaknikhil/gpdb,0x0FFF/gpdb,arcivanov/postgres-xl,randomtask1155/gpdb,ovr/postgres-xl,lpetrov-pivotal/gpdb,tangp3/gpdb,janebeckman/gpdb,ovr/postgres-xl,adam8157/gpdb,postmind-net/postgres-xl,postmind-net/postgres-xl,oberstet/postgres-xl,50wu/gpdb,adam8157/gpdb,kaknikhil/gpdb,lpetrov-pivotal/gpdb,kaknikhil/gpdb,kaknikhil/gpdb,yuanzhao/gpdb,ahachete/gpdb,edespino/gpdb,postmind-net/postgres-xl,techdragon/Postgres-XL,Quikling/gpdb,ashwinstar/gpdb,edespino/gpdb,tangp3/gpdb,janebeckman/gpdb,Chibin/gpdb,Quikling/gpdb,yazun/postgres-xl,cjcjameson/gpdb,adam8157/gpdb,lisakowen/gpdb,rubikloud/gpdb,xuegang/gpdb,chrishajas/gpdb,Quikling/gpdb,tangp3/gpdb,atris/gpdb,xuegang/gpdb,atris/gpdb,rvs/gpdb,randomtask1155/gpdb,pavanvd/postgres-xl,techdragon/Postgres-XL,kmjungersen/PostgresXL,0x0FFF/gpdb,lisakowen/gpdb,ahachete/gpdb,adam8157/gpdb,50wu/gpdb,chrishajas/gpdb,janebeckman/gpdb,rubikloud/gpdb,xinzweb/gpdb,chrishajas/gpdb,greenplum-db/gpdb,50wu/gpdb,foyzur/gpdb,cjcjameson/gpdb,CraigHarris/gpdb,xinzweb/gpdb,jmcatamney/gpdb,Quikling/gpdb,rvs/gpdb,cjcjameson/gpdb,CraigHarris/gpdb,zaksoup/gpdb,jmcatamney/gpdb,royc1/gpdb,lpetrov-pivotal/gpdb,randomtask1155/gpdb,CraigHarris/gpdb,rubikloud/gpdb,edespino/gpdb,yuanzhao/gpdb,tangp3/gpdb,techdragon/Postgres-XL,ahachete/gpdb,cjcjameson/gpdb,chrishajas/gpdb,yuanzhao/gpdb,jmcatamney/gpdb,Chibin/gpdb,rvs/gpdb,atris/gpdb,chrishajas/gpdb,pavanvd/postgres-xl,edespino/gpdb,rubikloud/gpdb,xuegang/gpdb,atris/gpdb,0x0FFF/gpdb,snaga/postgres-xl,0x0FFF/gpdb,arcivanov/postgres-xl,xuegang/gpdb,chrishajas/gpdb,cjcjameson/gpdb,greenplum-db/gpdb,ovr/postgres-xl,lintzc/gpdb,rubikloud/gpdb,lisakowen/gpdb,kmjungersen/PostgresXL,edespino/gpdb,ashwinstar/gpdb,yazun/postgres-xl,royc1/gpdb,cjcjameson/gpdb,atris/gpdb,ahachete/gpdb,oberstet/postgres-xl,adam8157/gpdb,edespino/gpdb,pavanvd/postgres-xl,snaga/postgres-xl,kmjungersen/PostgresXL,randomtask1155/gpdb,janebeckman/gpdb,rvs/gpdb,yuanzhao/gpdb,0x0FFF/gpdb,lisakowen/gpdb,randomtask1155/gpdb,Quikling/gpdb,zeroae/postgres-xl,ahachete/gpdb,Chibin/gpdb,CraigHarris/gpdb,greenplum-db/gpdb,xuegang/gpdb,rvs/gpdb,royc1/gpdb,lpetrov-pivotal/gpdb,Postgres-XL/Postgres-XL,CraigHarris/gpdb,techdragon/Postgres-XL,ahachete/gpdb,kaknikhil/gpdb,Quikling/gpdb,Chibin/gpdb,arcivanov/postgres-xl,greenplum-db/gpdb,greenplum-db/gpdb,tangp3/gpdb,adam8157/gpdb,lintzc/gpdb,cjcjameson/gpdb,janebeckman/gpdb,zaksoup/gpdb,ahachete/gpdb,edespino/gpdb